How do you confront your crush on somebody?

How do you confront your crush on somebody?
Life is so transient ,while you will recognize so many people around the world,and of course it is difficult to love one person only,and it will be natural to like other people who are smart or kind .Now,I have a crush on my friend,but he is my boyfriend's good friend,I know he likes me as well ,but we know it is impossible for us to be together.He knows he could't be sorry to his goodfriend,I understand him.We have no choice but give up and forget this relationship.When you have a crush on somebody ,no matter who you are ,no matter who he is,how do you confront this relationship